1. Field of the Invention
The present invention relates to an image forming apparatus, an image forming method for the image forming apparatus, and a program.
2. Description of the Related Art
Color image forming apparatuses that have an electrophotographic system use a direct transfer method for directly transferring an image formed on a photosensitive element onto a sheet and an indirect transfer method for temporarily transferring images formed on a plurality of photosensitive elements for each color onto an intermediate transfer belt so as to combine the colors and then transfer the images transferred onto the intermediate transfer belt onto a sheet. A technology is disclosed in which, as a unit that performs alignment in a color image forming apparatus that, out of the above transfer methods, transfers a black image onto a transfer sheet by the direct transfer method and transfers yellow, magenta, and cyan images formed on an intermediate transfer belt onto a transfer sheet by the indirect transfer method, a configuration is such that the time required for conveying images from a position where images formed on a plurality of photosensitive elements for each color are transferred onto an intermediate transfer belt to a position where the images transferred onto the intermediate transfer belt are transferred onto a sheet is an integral multiple of a period of a rotator that rotates the intermediate transfer belt, whereby the speed fluctuation of the intermediate transfer belt is reduced and misalignment is also reduced (see Japanese Patent Application Laid-open No. 2008-90092).
According to the technology disclosed in Japanese Patent Application Laid-open No. 2008-90092, the occurrence of misalignment due to speed fluctuation of the intermediate transfer belt can be prevented; however, consideration is only given to the speed fluctuation of the intermediate transfer belt, not to the speed fluctuation of a transfer-sheet conveying belt that conveys the transfer sheet to a position where an image transferred onto the intermediate transfer belt is transferred onto the transfer sheet, and therefore the problem of the occurrence of misalignment occurs.